Double fabrics have been knitted together since the turn of the century. In 1902, Scott & Williams was granted U.S. Pat. No. 709,734 on a knitted fabric comprising two webs practically independent of each other but united by causing the yarn which constitutes one of the webs to engage with the other web at intervals. Tucking the two webs together in this fashion produces a double web fabric joined together. The double web fabric exhibits many desirable characteristics, not the least of which is the ability to have an outer face formed of fibers which are distinctly different from the fibers which form the inner face. At the time of the original invention, a wool outer face combined with a cotton inner face provided a desirable combination of warmth and comfort which was not available in the absence of two distinct webs.
Over the years, the composition of fabrics formed in this fashion has developed so as to produce a wide variety of desirable so-called bi-ply fabrics. For example, the two plies of fabrics are substantially independent of one another so that each of the fabrics may be knitted with characteristics which complement the other and the double knitting produces a composite bi-ply fabric which has characteristics which are not possessed by either ply alone.